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Different land use management practices e.g. native forest vegetation, pastures and the agricultural management practices (e.g. tillage, cropping system, crop residue mulching and fertilizer and manure application) influence the soil organic carbon pools, which has short term and long term implications on soil carbon dynamics. Field experiments were conducted in a sandy loam soil of the Indian Agricultural Research Institute, New Delhi research farm during the kharif season (July to October) of 2012 and 2013 with the objective to study the short term (2 years) impact of irrigation, crop residue mulch and nitrogen management in maize on soil organic carbon pools and to identify the best management practice in terms of Carbon Management Index (CMI). Maize (cv. HQPM 1) was grown in a split-split plot design with two levels of irrigation (irrigated and rainfed) as main factor, two levels of mulch (No mulch and wheat residue at a rate of 10 Mg/ha as mulch) as sub factor and three levels of nitrogen (0, 75 and 150 kg N/ha) as subsub factor. The results showed that total organic carbon (TOC) increased by 40.5% in irrigation treatment compared to the rainfed treatment for the 0–5 cm soil depth after 2nd year of cropping. Application of crop residue mulch significantly increased the TOC concentration by 14.9% at 0–5 cm soil depth compared to the no mulch treatment. Crop residue mulch also significantly increased carbon stratification ratio (SR) by 9.2% compared to no mulch treatment for the same depth. Nitrogen application at 150 kg/ha significantly increased TOC concentration at 0–5 cm soil depth by 22.2% and 7.8% over control and 75 kg/ha, respectively. Water stable aggregate associated carbon concentration in large macro-aggregates and micro-aggregates increased significantly by 16.7% and 11.8%, respectively due to crop residue mulching. Application of crop residue mulch resulted in significant increase in labile and non-labile pools of carbon at 0–5 cm soil depth compared to the no mulch treatment, and among the labile pools of carbon, the maximum increase was recorded in very labile (VL) pools. The Carbon Lability Index (CLI) decreased whereas Carbon Pool Index (CPI) and Carbon Management Index (CMI) increased due to irrigation and crop residue mulch application. Application of 75 kg N/ha resulted in significantly higher CMI than that of 150 kg N/ha at 0–5 and 5–15 cm soil depth. So maize may be grown under irrigated condition with wheat residue mulch at a rate of 10 Mg/ha and 75 kg N/ha to achieve higher total organic carbon pool and labile pools of carbon, better Carbon Management Index. [ABSTRACT FROM AUTHOR]

There is a need to characterize the water stress in wheat using suitable indices, which will help us to find out the water stress sensitive period for efficient use of irrigation water. Recently indices based on canopy spectral reflectance, which are non destructive, fast and reliable, are being used effectively to characterize the water stress. A field experiment was carried out during the year 2010–2012 in split plot design with four levels of irrigation (irrigation at 0.4 IW/CPE, 0.6 IW/CPE, 0.8 IW/CPE and 1.0 IW/CPE, IW = 6 cm) as main plot factors and three sources of nitrogen (100% N from urea, 50% N from urea and 50% N from farmyard manure (FYM) and 100% N from FYM) as subplot factors. The objective of the study was to find out the water stress indices best correlated with wheat grain and biomass yield, to determine the optimum growth stage for measurement of water stress indices and to predict the grain and biomass yield of wheat based on water stress indices. The canopy reflectance was measured in the spectral range of 350–2500 nm with 1 nm bandwidth with the help of hand held ASD FieldSpec Spectroradiometer at seven phenostages, viz. , crown root initiation (CRI), tillering, booting, flowering, milk, soft dough and harvesting stage. Then different water stress indices were computed as: water index (WI) = R 970 / R 900 , normalized water index-1 (NWI-1) = ( R 970 − R 900 )/( R 970 + R 900 ), normalized water index-2 (NWI-2) = ( R 970 − R 850 )/(R 970 + R 850 ), normalized water index-3 (NWI-3) = ( R 970 − R 920 )/( R 970 + R 920 ), normalized water index-4 (NWI-4) = ( R 970 − R 880 )/( R 970 + R 880 ), where R and the subscript numbers indicate the light reflectance at the specific wavelength (in nm). It was observed that spectral reflectance based water indices recorded at the milk stage, WI and NWI-1 were significantly negatively correlated with the grain yield and NWI-1 and NWI-3 were significantly negatively correlated with the biomass yield of wheat, having maximum correlation coefficients. Validation of regression model based on NWI-1 could account for the maximum 87.5% variation in the observed grain yield and the regression model based on WI could account for maximum 89.2% variation in the observed biomass yield of wheat with minimum root mean square errors. So the regression models based on NWI-1 and WI recorded at milk stage can be successfully used to predict the grain and biomass yield of wheat in advance. [ABSTRACT FROM AUTHOR]

Abstract: The effect of sole application of inorganic fertilizers (NPK) (N:P:K:: 30:26:25kgha−1) and combined application of farmyard manure (FYM) @ 4Mgha−1 and inorganic fertilizers (NPK+FYM) vis-a-vis non-application of fertilizers and manures (control) on changes in soil physical properties and plant growth characteristics of soybean (cv. JS 335) was studied in a deep Vertisol at the Indian Institute of Soil Science, Bhopal during the year 2001–2004. The results indicated that conjunctive use of recommended dose of fertilizer and farmyard manure (NPK+FYM) resulted in significant (P <0.05) decrease of bulk density (9.3%), soil penetration resistance (42.6%) and increase in hydraulic conductivity (95.8%) and mean weight diameter of the water stable aggregates (13.8%) and soil organic carbon content (45.2%) compared to control. Among the aggregates, in macro-aggregate fraction (250–500μm and 500–1000μm size fraction) and in large macro-aggregate fraction (>2000μm) maximum soil organic carbon concentration was recorded under NPK+FYM. The root mass of soybean was mostly (98%) confined to 15cm soil depth. Combined application of NPK and FYM recorded significantly higher (P <0.05) root length density and root mass density of soybean in the 0–15cm soil layer at flowering stage over NPK (28 and 65%) and control (63 and 175%). The root length density of soybean was significantly negatively correlated with the penetration resistance (r =0.98, P <0.05). Application of FYM @ 4Mgha−1 with NPK significantly (P <0.05) improved the biomass partitioning towards pod over NPK and control. The grain yield, water use efficiency and nitrogen use efficiency of soybean under NPK+FYM were significantly (P <0.05) higher than NPK and control. The total above ground biomass and the leaf area index at R8 stage could account for respectively, 89 and 63% variation in grain yield of soybean. Therefore in every crop season, integrated use of farmyard manure at 4Mgha−1 and recommended dose of chemical fertilizers may be practised in Vertisols for improving soil physical environment and achieving higher soybean productivity through efficient utilization of water and nutrients. [Copyright &y& Elsevier]

Abstract: In Vertisols of central India erratic rainfall and prevalence of drought during crop growth, low infiltration rates and the consequent ponding of water at the surface during the critical growth stages are suggested as possible reasons responsible for poor yields (<1tha−1) of soybean (Glycine max (L.) Merr.). Ameliorative tillage practices particularly deep tillage (subsoiling with chisel plough) can improve the water storage of soil by facilitating infiltration, which may help in minimizing water stress in this type of soil. In a 3-year field experiment (2000–2002) carried out in a Vertisol during wet seasons at Bhopal, Madhya Pradesh, India, we determined infiltration rate, root length and mass densities, water use efficiency and productivity of rainfed soybean under three tillage treatments consisting of conventional tillage (two tillage by sweep cultivator for topsoil tillage) (S1), conventional tillage+subsoiling in alternate years using chisel plough (S2), and conventional tillage+subsoiling in every year (S3) as main plot. The subplot consisted of three nutrient treatments, viz., 0% NPK (N0), 100% NPK (N1) and 100% NPK+farmyard manure (FYM) at 4tha−1 (N2). S3 registered a significantly lower soil penetration resistance by 22%, 28% and 20%, respectively, at the 17.5, 24.5 and 31.5cm depths over S1 and the corresponding decrease over S2 were 17%, 19% and 13%, respectively. Bulk density after 15 days of tillage operation was significantly low in subsurface (15–30cm depth) in S3 (1.39mgm−3) followed by S2 (1.41mgm−3) and S1 (1.58mgm−3). Root length density (RLD) and root mass density (RMD) of soybean at 0–15cm soil depth were greater following subsoiling in every year. S3 recorded significantly greater RLD (1.04cmcm−3) over S2 (0.92cmcm−3) and S1 (0.65cmcm−3) at 15–30cm depth under this study. The basic infiltration rate was greater after subsoiling in every year (5.65cmh−1) in relation to conventional tillage (1.84cmh−1). Similar trend was also observed in water storage characteristics (0–90cm depth) of the soil profile. The faster infiltration rate and water storage of the profile facilitated higher grain yield and enhanced water use efficiency for soybean under subsoiling than conventional tillage. S3 registered significantly higher water use efficiency (17kgha−1 cm−1) over S2 (16kgha−1 cm−1) and S1 (14kgha−1 cm−1). On an average subsoiling recorded 20% higher grain yield of soybean over conventional tillage but the yield did not vary significantly due to S3 and S2. Combined application of 100% NPK and 4t farmyard manure (FYM) ha−1 in N2 resulted in a larger RLD, RMD, grain yield and water use efficiency than N1 or the control (N0). N2 registered significantly higher yield of soybean (1517kgha−1) over purely inorganic (N1) (1392kgha−1) and control (N0) (898kgha−1). The study indicated that in Vertisols, enhanced productivity of soybean can be achieved by subsoiling in alternate years and integrated with the use of 100% NPK (30kg N, 26kg P and 25kg K) and 4t FYM ha−1. [Copyright &y& Elsevier]

The frequency, size and rate of development of cracks influence the transport of water, nutrients and gases in the soil profile and plant growth processes in Vertisols. Despite their importance, studies on characterising cracks in Vertisols of India are limited. This study attempts to evaluate the influence of different tillage practices, nutrient management and cropping systems on cracking behaviour of a Vertisol in central India. The length, depth, width, area and volume of cracks were recorded after the harvest of the wet season crops, i.e. soybean (Glycine max L.) and rice (Oryza sativa L.) from three ongoing tillage experiments with three different cropping systems, i.e. soybean–wheat (Triticum aestivum L.), soybean–linseed (Linum usitatissimum L.) and rice–wheat. The results revealed that all the crack parameters were significantly negatively correlated with the water content of the 0–15 cm soil layer and, crack width and crack volume were significantly positively correlated with the bulk density of the 0–15 cm soil layer. Gravimetric water content and bulk density of the 0–15 cm soil layer together explained 79% variation in the crack volume. The crack volume was significantly negatively correlated (r=0.86,P=0.01) with the root length density of the previous soybean crop. Rice grown under puddled condition significantly enhanced different crack parameters viz., length, depth, width, surface area and volume of the cracks over nonpuddled direct seeded rice. Sub-soiling practised in soybean under the soybean–linseed system significantly reduced the width, depth, length and surface area of cracks by 12.5, 10, 5 and 12%, respectively, over conventional tillage. No tillage practised in soybean under soybean–wheat system resulted in significant increase in width, depth and volume of the cracks but decrease in length and surface area of cracks over conventional tillage and mould board tillage practice. Application of manure reduced the magnitude of different crack parameters in soybean–linseed cropping system. Thus cracking in Vertisols can be favourably managed by the selection of proper tillage practice, cropping system and organic manure amendments. [Copyright &y& Elsevier]

The variation of water depth, during propagation of tidal waves through a channel, changes the hydraulic friction as well as hydraulic inertia in a non-linear fashion. The non-linear change of hydraulic inertia introduces a distortion in the propagating wave which advances the wave crest, and retards the wave trough. So far, this effect had been neglected in the electronic analog model of a tidal channel.
In this paper an attempt has been made to develop an interia simulator with proper functional dependence as in the prototype. [ABSTRACT FROM AUTHOR]

In the design of an electronic analogue model of a tidal channel, the hydraulic parameters of the channel have to be scaled properly. In the method of scaling previously discussed the hydraulic parameters were all assumed to be linear, which constituted a drawback to the method, especially because the non-linearities in hydraulic friction are too considerable to be neglected. In this paper an attempt has been made to scale the non-linear hydraulic friction simulator in accordance with the prototype parameters. The outlines of the setting up of a complete analogue model together with some results that can be obtained with the help of the model are also given. [ABSTRACT FROM AUTHOR]

Discretizing of fields is important in analogue simulation because it permits the construction of analogue models using lumped electrical elements, which are easier to design, manipulate and specify with high accuracy and precision. Such a process Of lumping in turn introduces an error in the propagation characteristics of the analogue model simulating the prototype. In this paper an attempt has been made to evaluate the error in the propagation characteristics of the lumped analogue model of a tidal channel. [ABSTRACT FROM AUTHOR]

Propagation of tidal waves in a tidal channel and that of electromagnetic waves in an electrical transmission line are similar, as can be seen by noting the similarities between the differential equations which characterize the two systems. The latter can be used as the analogue model of the former, provided the variables, constants and parameters are properly sealed for the corresponding quantities available in the model. This paper describes the method of scaling to relate the corresponding parameters and variables in the two systems. [ABSTRACT FROM AUTHOR]

In an electrical analog of a tidal channel the simulation of friction by electrical resistance poses a serious problem, since hydraulic friction between two sections depends not only on the discharge but also on the existing water depth, while a normal electrical resistance element is independent of either current flowing through it or of the potential difference across it. in this paper an attempt has been made to develop an analog electronic circuit, using transistors and diodes, the resistance of which varies in the same non-linear fashion as does friction in its prototype. [ABSTRACT FROM AUTHOR]

This study assessed the effect of land use systems (rice-fallow, bamboo, mandarin and forest) along an altitude gradient (<500, 500–1000 and > 1000 m asl) and soil depth (0–15, 15–30 and 30–45 cm) on C stability in naturally occurring clay-organic complex (NOCOC) and their relationship with soil properties. The C stability in NOCOC (1/k) was determined from desorption rate constant (k) of humus-C by sequential extraction and was correlated with soil properties across the altitude. The C stability in NOCOC decreased (34%) with increasing soil depth from 0–15 to 30–45 cm. Across the altitudes, highest C stability in NOCOC was at > 1000 m asl (8.37 h) which was 12.7 and 9.4% higher than 500–1000 and < 500 m asl, respectively. Irrespective of soil depth and altitude, forest (5.30 h) showed the greatest C stability in NOCOC followed by mandarin (4.64 h), bamboo (4.20 h) and rice-fallow (3.85 h). Measurable soil properties could explain 90–94% variability of C stability in NOCOC across the altitude. Furthermore, C stability in NOCOC increased macroaggregate formation (0.25 mm) and ensured greater physical, chemical and microbial protection of organic C in soil. [ABSTRACT FROM AUTHOR]

Carbon (C) sequestration in soil is limited by the soil's maximum C carrying capacity (C m) and C saturation deficit (S d). These two parameters have enormous implication for choosing appropriate management strategies to increase a soil's C sequestration potential (CSP). The present study aims to estimate the C m and S d of two Alfisols from Bhubaneswar (Alfisol-BHNS) and Pattambi (Alfisol-PTMB) and two Vertisols from Parbhani (Vertisol-PRBN) and Junagadh (Vertisol-JNGD) in India with a history of long-term manuring and fertilization practices. Both the Alfisols maintained a rice-rice cropping system whereas the Vertisols had a soybean-safflower and groundnut-wheat cropping system, respectively. Irrespective of soil types and cropping systems, the soil organic C (SOC) content and stock were the highest in the treatment receiving 100% of recommended dose of NPK combined with 10 Mg ha-1 well decomposed farmyard manure (100%NPK+FYM). The mean annual estimated return of C (MAERC) across the soil types followed the order 100%NPK + FYM> 150%NPK = 100%NPK +Lime (Agricultural grade, purity 80%)> 100%NPK > 50%NPK > control. The C m at 0–30 cm soil depth was 39.3, 21.7, 47.6 and 25.0 Mg ha-1, respectively for Alfisol-PTMB, Alfisol-BHNS, Vertisol-JNGD and Vertisol-PRBN. The S d value was the highest in the control treatment and lowest in100% NPK + FYM treatment, signifying a higher CSP of the former soil than the later. Therefore, 100%NPK +FYM treatment would require a minimum threshold level of C addition to maintain the SOC at equilibrium. The estimated minimum threshold limit of annual C input (A E) to preserve the existing SOC level was 1.84, 0.39, 1.57 and 0.90 Mg ha-1 yr-1 for Alfisol-PTMB, Alfisol-BHNS, Vertisol-JNGD and Vertisol-PRBN, respectively. Alfisol-PTMB and Vertisol-JNGD showed a higher CSP than Alfisol-BHNS and Vertisol- JNGD because the former two soils had higher S d values than the later soils. The MAERC, climate, soil texture and clay mineralogy largely influenced the SOC sequestration and C m values. An integrated application of 100%NPK with either lime or FYM is recommended to maintain the sequestration and stabilization of SOC in the studied soils. The CSP of the soils could be further increased via innovative approaches such as increasing soil's reactive mineral contents to lock additional C. • The maximum carbon (C) carrying capacities of Alfisols and Vertisols were estimated. • Higher carbon saturation deficit marked higher carbon sequestration. • Application of 100%NPK + lime/FYM showed highest build-up of carbon in soil. • Carbon input dosage (including FYM) should be soil C saturation level based. • Complex interaction of C input, clay minerology, texture effects soil C stability. [ABSTRACT FROM AUTHOR]

Abstract: Intercropping system of cereals with legume is common in semi-arid tropics of India. However, little attention has been paid to assessing nutrient competition in the system. Seasonal changes in relative dry matter yield (RDY), relative nitrogen yield (RNY), relative phosphorus yield (RPY) and relative potassium yield (RKY) are useful indices to estimate the N, P and K status in intercropping system. The competitive effect of soybean (Glycine max L.) in association with sorghum (Sorghum bicolor L. Moench) was assessed using these indices under six nutrient treatments (0, 75% NPK, 100% NPK, 75% NPK+5Mg farmyard manure, 75% NPK+5Mg phosphocompost and 75% NPK+1.5Mg poultry manure) from a 5-year field experiment conducted in a N and P deficient Vertisol of Central India. The RDY and RNY of sorghum were greater than the values of RDY and RNY of soybean indicating inter-species competition for N between component crops, peak competition being at 80 days after sowing (DAS). Using the concept of RDY and RNY, it was observed that having coincided the maturity period and peak demand for N of both the crops, soil N was exhausted by sorghum because of its strong competitive ability and N was liming for soybean at 80 DAS. Strong competitive ability of sorghum was also evident from higher biomass, root mass, root length density and contribution to the mixture yield. Once sorghum entered its maturity phase, its competitive effect on soybean was greatly reduced. Competition for P between two species is more prominent up to 60 DAS and P was not limiting to none of the species after 60 DAS as the RPY values were equal to corresponding RDY values. Based on RKY value, none of the component species suffered from K deficiency at any stage even if it was not applied. This implied that competition exists for soil N and P but not for K up to 60–80 DAS in soybean/sorghum intercropping system. The result showed that competition between two crops measured in terms of RNY, RPY and RKY under organic-fertilizer was less; however, recorded higher soybean equivalent yield and monetary advantage index than inorganic-fertilizer. The study thus suggests that in soybean/sorghum intercropping system to minimize competition between two crops in N and P deficient Vertisol, application of 75% NPK+FYM/poultry manure/phosphocompost is a viable nutrient management option. [Copyright &y& Elsevier]

Abstract: Distillery effluent, a foul smelling, dark coloured by-product of distillery industries, is usually applied as irrigation water or as an amendment to arable land in some areas which are in the vicinity of the distillery industries. A field experiment on soybean–wheat system was conducted for 3 consecutive years in a Vertisol of central India to evaluate the effect of distillery effluent (DE) as an amendment on soil properties and crop productivity. The treatments were control (no fertilizer or manure or DE, T1), 100% NPK+FYM @ 4Mgha−1 to soybean (T2) and four graded levels of DE, viz.: 2.5cm DE to soybean and wheat on residual nutrition (T3), 2.5cm DE to soybean and 1.25cm to wheat (T4), 5cm DE to soybean and wheat on residual nutrition (T5), 5cm DE to soybean and 2.5cm to wheat (T6). The organic carbon, microbial biomass carbon and electrical conductivity (EC) of the surface (0–10cm) soil increased significantly with application of DE compared to T1 and T2, but the soil pH was not affected. The EC increased from 0.47dSm−1 and 0.58dSm−1, respectively, in T1 and T2 to 1.52dSm−1 in T6, where highest dose of DE was applied. This indicated a slight build-up of salinity with DE application. The application of DE showed a significant improvement in the physical properties of the soil. The mean weight diameter (MWD), saturated hydraulic conductivity, water retention at field capacity and available water content were significantly (P <0.05) higher, while bulk density (BD) and penetration resistance of the surface soil were significantly lower (P <0.05) in all DE treated plots except in T3 than those in T1 and T2. The fractions of WSA of more than 1mm diameter in T6, T5 and T4 were, respectively, 141%, 107% and 116% more than the control. The MWD showed a positive linear relationship with the organic carbon (r =0.84**) and microbial biomass carbon (r =0.90**) of the soil. A significant (P <0.01) negative linear relationship (r =0.70**) was found between soil organic carbon and BD. Except T3, all the DE treated plots recorded significantly higher total and microporosity of the soil than control. Water retention at permanent wilting point and macroporosity of the soil were not affected by treatment. The seed yield of soybean in all the DE treatments was similar with T2 (1.86Mgha−1) but significantly more than control (1.28Mgha−1). The DE application levels have not affected the seed yield of soybean. In wheat highest grain yield was recorded in T2 (3.47Mgha−1), which was similar with T4 (3.16Mgha−1), T5 (3.22Mgha−1) and T6 (3.46Mgha−1). DE application up to T4 level was found suitable from productivity, salinity and sustainability point of view. The study showed that judicious application of DE as an amendment to the agricultural field could be considered as a viable option for safe disposal of this industrial waste. [Copyright &y& Elsevier]

Abstract: In Vertisols of the semi-arid tropics lack of optimum soil water and low soil temperature (<18°C) during germination, and high soil temperature (>37°C) during pod development stage has been a major barrier to realizing yield potential of summer groundnut. Seven field experiments (comparing straw with polythene, 50μm gauge mulch, duration of retention of polythene mulch, testing the combined effect of straw and polythene mulch, N management in straw mulch and field demonstration) were carried out from 1992 to 1999 in a sequence to identify a suitable mulch material, which was socially and economically acceptable and could overcome soil water and soil temperature related problems for summer groundnut. In general, straw mulch (wheat or paddy) produced more pod (17–24%) and haulm yields (16%) of groundnut than polythene mulch (black or transparent) and no mulch because of favourable soil water and soil temperature, earlier seedling emergences, more flower and mature pods numbers, lower bulk density and less weeds. We observed that groundnut plants showed N deficiency under wheat straw mulch at the early stage (up to 60 days after sowing). However, towards maturity N deficiency occurred at the early stage had no significant negative impact on pod yield of groundnut because the plants recovered N deficiency and had greater chlorophyll content and pod yield. This is presumed to be associated with bio-availability of macro and micronutrient during decomposition of organic mulch. The pod yield of groundnut under black polythene was higher than under transparent polythene. The polythene mulch increased soil temperature by 4–5°C through out the crop growth (germination to maturity), which increased seeding emergence but was detrimental to pod setting and pod development (soil temperature exceeded 40°C). Thus, the benefit of polythene was only observed when it was retained up to podding stage, but not up to harvest. The combined application of wheat straw and black polythene out-yielded sole application of wheat straw mulch but the former was 45% less profitable than the later one because of the cost of polythene. Wheat straw mulch was finally demonstrated to the farmer''s field. It was found that sacrificing 5t wheat straw as cattle feed, farmers on return get additional 0.47tha−1 legume fodder due to mulching which is nutritionally superior quality fodder in terms of crude protein, phosphorus content, crude fiber, ash and silica content compared to wheat straw as cattle feed. Thus, 16% additional production of highly nutritive groundnut haulm due to mulching has a significant implication on (i) nutritional fodder security, especially during the dry season when green fodder is costly and its availability is limited, and (ii) additional income of Rs. 3935ha−1 from mulch. These two considerations, apart from solving temperature related problems convinced 32 farmers of Vadhvi and Zanjarda village of Junagadh district, Gujarat for adoption of wheat straw technology for summer groundnut in about 50ha areas. [Copyright &y& Elsevier]

Abstract: Low native nitrogen (N) and phosphorus (P) coupled with imbalanced nutrient application is a major constraint limiting productivity of intercropping systems on Vertisols of the semi-arid tropical India. In a 3-year field experiment competition behaviour of component crops for nutrients use in soybean/pigeonpea intercropping system was assessed based on relative yield (RY), relative nitrogen yield (RNY) and relative phosphorus yield (RPY) under three nutrient levels (0 NPK, 100% NPK (N:P:K=30:26:25kgha−1) and 100% NPK+4t FYMha−1). The result showed that before soybean harvest, the RY and RNY of soybean were greater (1.0) than the corresponding values of RY and RNY of pigeon pea (0.6). This implied that competition exists for soil N between the component crops during the first half of the cropping system. It was observed that soybean harvest did not coincide with peak flowering of pigeonpea, the stage when biological nitrogen fixation (BNF) was maximum. Thus, BNF dependency of pigeonpea was low before soybean harvest and the plants suffered from N deficiency more when no fertilizer-N was applied and diminished at a high-N level. Pigeon pea attained its peak flowering after the harvest of soybean and increased its dependency on BNF when soil N was exhausted by soybean. Thus, after the harvest of soybean, RY and RNY of pigeon pea gradually increased and approached 1.0 at maturity at all nutrient levels. The RPY values showed that phosphorus was not the limiting factor to any of the crop in the system even if it was not applied. The study thus suggests that in the soybean/pigeonpea intercropping system, N is a limiting factor for growth of pigeonpea intercrop during the first half of its growth and application of 100% NPK (30kg N)+4t FYM could meet N demand of pigeonpea in N deficient soils as this nutrient management option gave higher yield, root length density and profit under soybean/pigeonpea intercropping system than 100% NPK and control. [Copyright &y& Elsevier]

Abstract: Opinions differ on the necessity of deep tillage for sustaining crop productivity in the rainfed Vertisols of the semi-arid tropics of central India. We conducted a field experiment for 3 years (2000–2002) with a factorial combination of three cropping systems (sole soybean, sole pigeonpea and soybean/pigeonpea intercropping in 2:1 row ratio) and three tillage practices (conventional, conventional+subsoiling in alternate years and conventional+subsoiling every year). Objectives were (i) to examine the effect of subsoiling Vertisols on sustaining yield of soybean/pigeon pea intercropping, and (ii) to assess the frequency of subsoiling for realizing maximum yield and profit. Though there was a reduction in growth and yield of intercrops, higher soybean equivalent yield (SEY) and area-time equivalent ratio (ATER) value in soybean/pigeonpea intercropping system as compared to sole soybean had a yield advantage. The average yield advantage in intercropping system was 60% higher than that from sole soybean. The yield advantage of intercropping system in terms of ATER was 7% greater with subsoiling than conventional tillage. The yield response to subsoiling was consistent over the period and on an average, subsoiling increased yield by 20%. The effect was associated with improved water storage and root length density. However, with respect to energy use efficiency and profit, the effect of subsoiling was comparable to conventional tillage. The variation in net return and benefit:cost ratio in subsoiling every year and subsoiling in alternate years in sole soybean and soybean/pigeonpea intercropping was not significant. However, in sole pigeon pea subsoiling every year out-yielded subsoiling in alternate years. The interactive effect of subsoiling and intercropping increased the yield by 21–25%. Thus, under rainfed cropping where drought of unpredictable intensity and duration is a prevailing feature, soybean/pigeon pea intercropping could be a promising option, especially when combined with subsoiling in alternate years. [Copyright &y& Elsevier]

A field experiment was conducted on deep vertisols of Bhopal, India to evaluate the manural potential of three organic manures: farmyard manure (FYM), poultry manure (PM), phosphocompost (PC) vis-a-vis 0%, 75% and 100% recommended dose of fertilizer-NPK and to find out the most productive cropping system at various combinations of organic manures and chemical fertilizers. The seed yield of intercrop soybean (population converted to 100%) was 8.7% less than sole soybean whereas the grain yield of intercrop sorghum was 9.5% more than that of sole sorghum. However, the productivity in terms of soybean equivalent yield (SEY) was relatively high in intercropping system. The increasing NPK dose from 0% to 100% significantly improved SEY in sole sorghum and soybean/sorghum intercropping system and the integrated use of organics and inorganics recorded significantly more SEY than inorganics. The effect of nutrient management followed the order; 75% NPK + 5 t FYM ha-1 > 75% NPK + 1.5 t PM ha-1 > 75% NPK + 5 t PC ha-1 > 100% NPK. Sorghum, both as sole and intercrop, responded more to PM while soybean to FYM. Application of 75% NPK in combination with PM or FYM or PC to preceding rainy season crops (soybean and sorghum) and 75% NPK to wheat produced significantly higher grain yield of wheat than those in inorganics and control indicating noticeable residual effect on the succeeding wheat crop and saving of 25% fertilizer-NPK. The effect of PC on rainy season crops was not as prominent as those of FYM and PM, but its residual effect on grain yield of wheat was comparable to those two organic manures. Among the cropping systems, soybean as preceding crop recorded the highest seed yield of wheat and was on a par with that of soybean/sorghum intercropping system. The yield of wheat following sorghum was the lowest. The total system productivity (TSP) was the highest in sorghum + soybean–wheat system and the lowest in the soybean–wheat system. [Copyright &y& Elsevier]

A field experiment was conducted on a deep Vertisol of Bhopal, India to compare root and shoot biomass, chlorophyll content, enzyme activity and nodulation in three cropping systems at three combinations of organic manure and inorganic-fertilizer: 75%NPK + 5 t farmyard manure (FYM), 75%NPK + 1.5 t poultry manure (PM), and 75%NPK + 5 t phosphocompost (PC) vis-a-vis 0%, 75% and 100% of fertilizer-NPK. In general, nodule number and its mass were lower in intercrop soybean than sole soybean. Also there was decrease in the nodule number with higher NPK dose. The FYM treated plots recorded 22.0% and 7.6% higher nodule mass than poultry manure and phosphocompost plots, respectively. Also, the total chlorophyll content was higher in organically treated plots than that in 100% NPK particularly at 30 days after sowing (DAS, pre-flowering). In sorghum the peak nitrate reductase (NR) activity was recorded at 60 DAS while in soybean it was at 30 DAS. The NR activity was higher in intercrop sorghum than that in sole sorghum. Maximum NR activity was observed in 100% NPK. Soybean/sorghum intercropping system recorded significantly higher root and shoot biomass than sole soybean and sorghum. The crop growth rates were relatively rapid during 30–60 DAS and followed the order; intercropping > sole sorghum > sole soybean. With the increase in NPK dose from 0% to 100% there was significant improvement in the dry matter (DM) production in sole sorghum and soybean/sorghum intercropping system. Soybean as preceding crop recorded the highest DM, chlorophyll content, NR activity in wheat while these values were the lowest in sorghum–wheat system. [Copyright &y& Elsevier]

An attempt has been made to assess the geoavailability of heavy metals in polluted soils using short sequential fractionation schemes. For this purpose, 25 composite soil samples were collected from various locations (across India) of which had a history of receiving sewage sludge, municipal solid waste, polluted river water and industrial effluents. Four composite soil samples were also collected from adjacent fields which had not received contaminated amendments. Zinc (Zn), copper (Cu), nickel (Ni), lead (Pb) and cadmium (Cd) were extracted from the soil solution plus exchangeable, carbonate bound, Fe and Mn oxides bound, and organic matter bound fractions. Copper (53.0%) was largely adsorbed by the organic fractions, while a significant amount of Zn (56.6%), Ni (78.4%), Pb (57.4%), and Cd (59.7%) was extracted from the Fe/Mn oxide bound fraction. Regression analysis revealed that water-soluble plus exchangeable pool of Zn, Cu, Ni, Pb and Cd contributed positively towards the uptake of these elements by spinach and wheat under pot experiment. Behaviour, transport and the ultimate fate of heavy metals in the soil environment depend largely on their association with different geochemical fractions of the soil which is related to the mineralogical origin of the metals. [ABSTRACT FROM AUTHOR]

The Indo-Gangetic Plains (IGP) of India is dominated with rice − wheat cropping system that occupies almost 10.5 million ha area. The sustainability of rice-wheat system is under threat due to numerous water-, nutrients-, weeds- and environment-related problems, mainly, due to the cultivation of rice. Suitable crop and soil management practices with a bias to conservation agriculture (CA) that can sustain soil and environmental health as well as improve crop and water productivity, are required for the Indian IGP. Maize can be a viable alternative to rice and a potential driver for diversification of rice-wheat system. The acreage of maize is on the increase in conventional and conservation agriculture-based cereal systems of India in recent years. Therefore, a field experiment, involving a maize ( Zea mays L.)-wheat cropping system was undertaken on a sandy clay loam soil for three years (2010–11 to 2012-13) in New Delhi to evaluate the impacts of CA on crop and water productivity, profitability and soil organic carbon (SOC) accumulation. There were five CA-based treatments in first year, and two treatments were introduced in second year (2011-12) onwards. The experiment was laid out in a randomized complete block design with three replications. In all the residue retention plots, wheat residue was retained in maize crop and maize residue was retained in wheat crop under zero till conditions. Results showed that the plots under permanent broad bed with residue (PBB + R) and without residue (PBB) resulted in ∼29 and ∼26% higher maize grain yield, respectively than conventional tillage (CT) (2.6 t ha −1 ), but wheat grain yields were comparable in all the treatments in first year. Maize grain yield in second year under PBB + R and zero tillage with residue (ZT + R) were 55 and 43% higher than CT plots (2.8 t ha −1 ). Three-year mean maize yields due to PBB + R and permanent narrow bed with residue (PNB + R) were 28 and 15% higher than that in CT plots (3.3 t ha −1 ). The PBB + R resulted in 11% higher two-year mean water productivity in maize than PBB (∼without residue), but both these treatments were comparable in this regard in wheat. The ZT + R plots resulted in 14% and 22% higher two-year mean water productivity, respectively in maize and wheat than ZT plots. Overall, the plots under PBB + R had 57% and 19% higher mean water productivities in maize and wheat, respectively compared with CT plots. Again, the PBB + R plots gave 12% higher two-year mean net returns compared with CT plots. With regard to net returns, the plots under permanent narrow bed with and without residue (PNB + R; PNB) were inferior to PBB, PBB + R, ZT and ZT + R plots. Retention of both-season crop residues could significantly improve SOC concentration in surface (0–5 cm) soil. The PBB + R resulted in highest SOC pool at 0–30 cm soil layer, which was significantly higher than that in CT. This system showed maximum carbon sequestration potential. Thus, this CA practice, which involves PBB + R is superior to other practice. This would save water through higher water-use efficiency, and lead to accumulation of more carbon in soil with higher sequestration potential, besides giving sustainable production through maize-wheat system over the years. This can be adopted across the IGP regions of India, where irrigated rice-wheat system is in practice, and in similar agro-ecologies of the tropics and sub-tropics under irrigated conditions. [ABSTRACT FROM AUTHOR]

Crop simulation is useful for characterizing and predicting the crop growth and yield due to abiotic stress and also climate change events at the national and international levels, under different agronomic management options. Crop simulation models will gain wider acceptance if they are robust, accessible and easy to use. To simulate the growth of wheat on a daily basis using inputs of weather, soil, variety and management practices, a web-based application of the crop simulation model ‘Web InfoCrop - Wheat’ was designed and developed at the Indian Agricultural Research Institute. The Web InfoCrop – Wheat model was developed using Visual Studio Express, SQL Server, NET framework 4.0 and hosted at http://InfoCrop.iari.res.in . This web-based model has separate modules for input variables, management conditions, and result outputs. Crop model users after registration without any payment, have the right to insert, edit or update and delete data within their private domains while the system manager alone has the administrative right to add data to the public domain, this will ensure authentic data to be available in the public domain. This is done mainly to ensure the availability of factual data to the public and also to maintain the privacy of the user data. The users can run the model to simulate the wheat crop growth and yield, at a single day interval or as defined. This web-based model performed well under different irrigation and nitrogen management practices for the observed and predicted yield and biomass with significant R 2 (0.958 and 0.947 respectively) and RMSE (0.054 and 1.318, respectively). Thus, the ‘Web InfoCrop – Wheat’ crop model provides an innovative and efficient approach to the evolving crop simulation model to be used as a decision support tool in the agricultural production system. [ABSTRACT FROM AUTHOR]

Highlights: [•] Optimization of date of sowing and cultivars of Indian mustard was done for enhancing productivity. [•] We attempted to compute radiation and water use efficiency of Indian mustard under varied crop growth environments. [•] We developed evapo-transpiration production function and radiation production function for Indian mustard. [Copyright &y& Elsevier]

Highlights: [•] Permanent broad-bed (PBB) planting effects on cotton–wheat system was evaluated. [•] Plots with PBB with residue had 3.1Mg higher wheat equivalent yield/ha/year than CT. [•] The PBB+residue (R) plots had 48% more mean system water productivity than CT. [•] The PBB+R plots had 36 and 13% more income than CT and permanent narrow-bed (PNB). [•] The PBB+R plots had higher mean water productivity than PNB+R, ZT and ZT+R plots. [ABSTRACT FROM AUTHOR]

Abstract: Balanced application of inorganic fertilizer and organic amendments greatly influence the accumulation of organic matter in soil and also influence the soil physical environment. An investigation was carried out to study the long-term impact of fertilizer and manure application in a soybean–wheat–maize (fodder) crop rotation on soil organic carbon status and physical properties of a vertisol (Typic Haplustert or Pellic Vertisols) in sub-humid sub-tropical India. Five treatments namely, control (no fertilizer and manure), 100% of the optimum rate for nitrogen (100% N), 50% of the optimum rate for nitrogen, phosphorus and potassium (50% NPK), 100% of the optimum rate for NPK (100% NPK) and 100% NPK+farmyard manure at 15Mgha−1 (100% NPK+FYM) from a long-term fertilizer experiment continuing at Jabalpur, India, were chosen for this study. Soil samples were collected from the topsoil horizon (0–15cm) of all the four replications of the selected five treatments in April 2000 after 28 crop cycles and analyzed for physical and chemical properties. The results showed that the soil organic carbon (SOC) content in 100% NPK and 100% NPK+FYM treatments increased, respectively, by 22.5 and 56.3% over the initial level (1.14kgm−2). The electrical conductivity, SOC content, aggregation, water retention, microporosity and available water capacity of the soil were increased while the bulk density was reduced significantly with the 100% NPK+FYM treatment over all other treatments. However, the use of imbalanced (100% N) and suboptimal rate of inorganic fertilizer (50% NPK) as compared to the unfertilized control showed no significant effect on the physical properties of the soil. The study indicates that application of balanced rate of fertilizers in combination with organic manure could sequester soil organic carbon in the surface layer, improve the soil physical environment and sustain higher crop productivity under this intensive cropping system. [Copyright &y& Elsevier]

Abstract: A field experiment was conducted on a Vertisol for three consecutive years (1998–2000) to study the effects of combined use of inorganic fertilizer (NPK) and organic manure (farmyard manure) on soil physical properties, water-use efficiency, root growth and yield of soybean [Glycine max (L.) Merr.] in a soybean–mustard cropping system. Application of 10Mg farmyard manure and recommended NPK (NPK+FYM) to soybean for three consecutive years improved the organic carbon content of the surface (0–15cm) soil from an initial value of 4.4gkg−1 to 6.2gkg−1 and also increased seed yield and water-use efficiency by 103% and 76%, respectively, over the control. The surface (0–15cm) soil of the plots receiving both farmyard manure and recommended NPK had larger mean weight diameter (0.50mm) and a higher percentage of water stable aggregates (55%) than both the inorganically fertilized (NPK) (0.44mm and 49%) and unfertilized control plots (0.41mm and 45.4%). The saturated hydraulic conductivity (13.32×10−6 ms−1) of the NPK+FYM treatment of the 0–7.5cm depth was also significantly greater than that of the NPK (10.53×10−6 ms−1) and control (8.61×10−6 ms−1) treatments. The lowest bulk density (1.18Mgm−3) in the 0–7.5cm layer was recorded in NPK+FYM whereas it was highest in the control plots (1.30Mgm−3). However, at sub-surface (22.5–30cm) layer, fertilizer and manure application had little effect on bulk density and saturated hydraulic conductivity. Root length density (RLD) up to the 30cm depth was highest in the NPK+FYM plots and it was 31.9% and 70.5% more than NPK and control plots. The RLD showed a significant and negative correlation (r =−0.88∗∗) with the penetration resistance. [Copyright &y& Elsevier]

Abstract: A field experiment was conducted at the Indian Institute of Soil Science, Bhopal, India to study the effect of combinations of amount of irrigation water and nutrient applications on crop growth, evapotranspiration (ET), yield and water use efficiency (WUE) of Indian mustard on a heavy clay soil in central India. Three irrigation regimes, viz. 60mm pre-sowing and no post-sowing irrigation (I60), 60mm pre-sowing plus 60mm post-sowing irrigation at flowering (I120), and 60mm pre-sowing plus 60mm post-sowing irrigation at rosette and at flowering stage (I180); and three nutrient application treatments, viz. no fertilizer/manure (F0), 100% NPK, i.e., total N, P and K rates of 60, 13.1 and 16.6kgha−1, respectively (F100) and 100% NPK plus 10Mgha−1 farmyard manure (F100M10) were tested in a split-plot design. The experiment was conducted for three consecutive seasons. The results revealed that treatment combinations of I180 ×F100M10, I120 ×F100M10 and I180 ×F100 maintained significantly greater leaf area index (LAI), above-ground dry matter (DM), ET, seed and biomass yield of the crop than other combinations. The duration of a LAI of ≥2.5 was more in F100 and F100M10 than in F0. Under I120, LAI remained ≥2.5 for 8 and 22 days in F100 and F100M10, respectively. This leaf area duration increased to 28 and 39 days in the corresponding nutrient treatments under I180. The root length, mass and volume densities were significantly higher in I180 than I120 and I60, and in F100M10 than F100 and F0. For a particular irrigation regime, ET increased significantly in F100 and F100M10 compared to F0. The maximum seed yield of 1736kgha−1 was recorded in I180 ×F100M10; and the seed yields under I120 ×F100M10 (1440kgha−1) and I180 ×F100 (1431kgha−1) did not vary significantly. The WUEseed and WUEbiomass decreased with the increase in amount of irrigation water. On the contrary, these WUE parameters increased in F100 and F100M10 compared to F0. The regression relationships of root length density on ET, and yield (both seed and biomass yield) on ET could be described by linear. Thus, I180 ×F100M10 is the best combination; and as the crop response to I120 ×F100M10 and I180 ×F100 was similar, this study concludes that application of organic manure along with 100% NPK fertilizers could reduce the need for one post-sowing irrigation without compromising the yield of this crop under deficit irrigation. [Copyright &y& Elsevier]

The study examines the energy requirement and energy input–output relationship of soybean-based crop production systems viz., soybean (Glycine max (L.) Merr.)–wheat (Triticum aestivum L.), soybean–mustard (Brassica juncea (L.) Czern & Coss.) and soybean–chickpea (Cicer arietinum L.) in central India. Using a pre-tested questionnaire, 135 farmers were selected through a multi-stage stratified random sampling technique. Results revealed that manures and chemical fertilizers (50.87%), seedbed preparation (18.30%) and sowing management (17.69%) consumed the bulk of the energy (operational and non-operational) for all crops, it was highest in soybean–wheat (23705±29.48 MJ ha−1) and the lowest in soybean–chickpea (15672±26.29 MJ ha−1). Wheat, with the highest grain productivity, produced the most biomass energy (78541±28.75 MJ ha−1) and highest grain-energy productivity (0.150 kg MJ−1). The total bioenergy output of the crop production systems followed the order: soybean–wheat (131277±29.26 MJ ha−1) > soybean–mustard (101661±28.91 MJ ha−1) > soybean–chickpea (92658±28.87 MJ ha−1). But this order was reversed for energy-use efficiency (EUE): soybean–chickpea (5.91)> soybean–mustard (5.86)> soybean–wheat (5.54). Specific energy was highest in soybean (9173 MJ t−1 grain) followed by mustard (8912 MJ t−1 seed), chickpea (7190 MJ t−1 grain) and wheat (6646 MJ t−1 grain) indicating that soybean is the most energy-investment intensive crop. Regarding energy intensiveness the results were contrary to EUE. Energy intensiveness (MJ Rs−1) was higher in wheat (1.40) followed by mustard (1.11), soybean (0.89) and chickpea (0.87) and the soybean–wheat system (1.13) emerged as the most energy-intensive system compared to soybean–mustard (0.97) and soybean–chickpea (0.88). Though the net return from soybean–wheat was marginally higher than other systems, the soybean–chickpea system is more suitable in the central ecological niche of India due to its low requirement for non-renewable resources, higher EUE and benefit–cost ratio. [Copyright &y& Elsevier]

The spectacular performance of Indian agriculture witnessed during the second half of the 20th century against the onslaught of rising demographic pressure is a vivid demonstration of the growing effectiveness of our agricultural research and development system. However, the issue of sustainability in agriculture still remains a question. Management of natural resources, especially soil and its fertility status and vegetation following suitable agronomic management practices for sustainable agricultural production, represents a most daunting task and is certainly going to receive much attention in the years to come. Many workers established functional relationships between nutrients and other agronomic factors at different locations in India but systematic compilation of those relationships is a rare effort. The present paper reviews the latest information on inter-relationships between nutrients and other agronomic factors (seed rate, planting density, age of the seedling, planting method, irrigation, weed control, tillage, bacterial inoculation and cultivar etc.) on field crops. Major findings of first and second order interactions are highlighted. None of the second order interaction was found significant; thus only first order interactions were discussed. The interactive effect of nutrients and seed rate varied with soil type. In sandy loam soil when 125 kg seed ha[sup -1] was used, wheat responded up to 60:30:40 kg N, P[sub 2]O[sub 5] and K[sub 2]O ha[sup -1], whereas in clay loam soil it was up to 80:40:30 kg N, P[sub 2]O[sub 5] and K[sub 2]O ha[sup -1] with the use of 25 kg higher seed rate. When chickpea was grown with a medium seed rate of 75 kg ha[sup -1] it responded up to 30 kg N and 60 kg P[sub 2]O[sub 5] ha[sup -1] saving 10 kg N and 20 kg P[sub 2]O[sub 5] in comparison to when a higher seed rate of 100 kg was used. Younger seedlings (20-25 days) performed better than old seedlings (35-40 days) in timely sown rice with the recommended dose of N,... [ABSTRACT FROM AUTHOR]

This study focuses on the use of synthetic and low cost carbon sources for enhanced biomass and lipid production from oleaginous yeast strains using batch and fed batch fermentation. Five strains were selected out of 20 strains which were all isolated from various habitats, on the basis of lipid accumulating potential using Sudan B black dye. The selected isolates were characterized and their lipid production was optimized by batch cultivation in waste extract. Gas chromatography analysis revealed that lipids from all isolated yeast strains contained mainly long-chain fatty acids such as oleic acid, palmitic acid, stearic acid and linoleic acid. On the basis of lipid profile and production, two most suitable oleaginous yeast strains were selected for further experiments, i.e. fed batch fermentation using glucose (control) and sugarcane molasses as feed. Using glucose as feed, 38.8 ± 0.9 g/L and 29.4 ± 0.2 g/L biomass dry cell weight (DCW) and total lipids were produced respectively, whereas with sugarcane molasses feed, 50 ± 1 g/L (DCW) biomass and 39.2 ± 0.6 g/L lipids were produced by Rhodosporidium toruloides ATCC204091. After transesterification the lipid profile was analyzed by GC–MS revealing suitability for use as a potential feedstock for biodiesel production. [ABSTRACT FROM AUTHOR]

• Conservation agriculture reduced sub-surface soil strength. • Total and microporosity improved, and therefore water retention under CA. • The impact was visible on the wheat root growth and development. • Soil aggregation improved, but marginal impact on soil organic carbon. The study compared conservation agriculture (CA) practice (no-tillage, crop residue cover on the surface and relay mung bean) with conventional intensive tillage system, in order to evaluate their effects on soil strength and water content, total porosity and pore-size distribution, roots and above-ground plant growth in wheat under a rice-wheat rotation. The experiment was started in the kharif season of the year 2010 in the research farm of the Indian Agricultural Research Institute, New Delhi, India. Observations were taken during 6th, 7th and 8th year of the rotation. The CA practice primarily reduced the sub-surface (15–30 and 30–45 cm) soil strength by 20–25% owing to 14% higher water content at this layer, and increased the total porosity (17%) and retention pores (22%). Soil aggregation and organic C improved primarily in the surface layer (0–15 cm). The modified soil physical properties led to better root growth, plant leaf area index and solar radiation interception, and higher grain and straw yields. The CA practice significantly contributed to improving the soil physical condition, especially in reducing the sub-surface compaction and improvement on root growth in wheat. This is significant in our quest to increase and sustain the rice-wheat production system in the Indian subcontinent. [ABSTRACT FROM AUTHOR]